Because of the lower price and higher functions of personal computers, increase of Internet contents, and diversity of network connecting devices such as cell phones and PDAs, there is an increasing number of opportunities to use local LAN and the Internet not only in corporate offices but also at home. Also the standards like HAVi and ECHONET are being arranged so that consumer electronics can be connected to networks.
In these circumstances, for example, in the case of a conventional AV digital network device, an interface for network connection and the function for connecting to the network are provided within the one device (see, for example, Patent Reference 1).
Also, for example, in the case of connecting to a network a conventional television that does not have the function for connecting to the network, an interface for network connection and the function for connecting to the network must be additionally provided. In other words, if these are added, this television can be connected to the network and new functions can be added to the television.    Patent Reference 1: JP-A-2002-16619 (page 3-4, FIG. 1)